Physiology 206 Lecture 16Outline of Last Lecture I. Collateral vesselsII. ShockIII. Heart attackIV. InfarctionV. Brain circulationVI. Respiration Outline of Current Lecture I. Thoracic cavityII. DiaphragmIII. Intercostal musclesIV. BronchiolesV. Obstructive disordersVI. Elasticity of lungsCurrent Lecture2/21/14- 1 ATM = 760mmHg- Pressure = N/volume- When air moves, moving down pressure gradientso Alternatively reducing and increasing pressure in alveolio Inspiration: inhaling (below atmospheric pressure)o Expiration: exhaling (above atmospheric pressure)- Thoracic cavityo If pressure decreases, pulls on lungs, expanding them-inhalationo If pressure increases, lungs can’t expand-exhalation (collapses lungs)o Pressure in thorax is below atmospheric pressure Keeps lungs from collapsing - Our natural tendency is to relaxThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Prevent collapse by keeping an air tight box, which is the thorax- Diaphragm-dome shaped muscle at the bottom of the thoracic cavityo Innervated by phrenic nerve- Intercostal muscles-around the ribso External intercostal muscles-outside of ribs Pulls ribs up and away from the spinal column when the muscle contracts Increases the volume in the thorax- Expiration is passive- When exercising:o Contract the external intercostals moreo Contract internal intercostals Pulls ribs inward Forced exhalation- Contract abdominal muscleso Push in abdomeno Push diaphragm upo Reduce thoracic volume- Poiseville’s Lawo Resistance to flow laws- Bronchioles account for most of resistance in air flowo Smooth muscles in wallso Can change diameter Change airway resistanceo Parasympathetic stimulation-bronchioles restricto Sympathetic stimulation-bronchioles relax Ex: asthma- Spastic contractions of bronchial smooth muscle- Increasing restriction of air flow- Must use muscles to exhaleo Obstructive disorder Airway resistance increaseso Other pulmonary disorders (Restrictive disorders) Resistance remains the same, volume reduced- Ex: pneumoniao Fluid leaks into the alveoli- Elasticity of lungso Elastic fibers-resist being stretchedo LaPlace’s Law Pressure (surface area) inside the sphere increases as the diameter
View Full Document
Unlocking...